Pouch compositions are known in the art. These compositions have an advantage in that they are easy to dose, handle, transport and store. Recently, water-soluble pouches that contain cleaning or fabric care compositions have become popular.
Typically, the film material that is used to prepare water-soluble pouches is relatively fragile, thin, and must have a high water-reactivity, so that the pouches can release the contained product quickly and completely without leaving residue. However, when the pouches are under stresses from production, packing, transportation, or have been exposed to a moist environment, the thin film material often leads to a premature release of the contained product. Furthermore, when the film material is exposed to low temperature conditions, the pouches may become susceptible to cold shock cracking and failure. Pouched commercial products currently on the market often encounter the above-mentioned difficulties.
Meanwhile, the packaging of additives and the dispensing of compositions into the pouches can also be problematic. For example, additives such as auxiliary agents are typically incorporated within pouched cleaning products as moisture sinkers, but they are often contained separately from the detergent in the same unit dose (i.e. pouch), so that each component can retain its stability prior to consumer usage. Furthermore, it is important to have the detergent in a free-flow, solid particulate form prior to its dispensing into a unit dose, so that a filling machine that packages the pouch can meter and dispense a precise amount of the detergent. Precision in metering and packaging is critical to ensure safety for consumer handling, to reduce the environmental impact caused by excessive cleaning products, and to reduce material cost. Currently, industry practices known in the art have not optimized the packaging of additives with detergent in the same unit dose, so that that the pouch is made to minimize cracks and leakage, and that the detergent composition remains free flowing to be packaged.
Various methods and compositions are known in the prior art, to treat water-soluble films or to reduce moisture within water-soluble pouches. One example is U.S. Pat. No. 7,259,134 to Beckholt et al., which discloses a multi-compartmented pouch that contains one compartment that has a liquid composition. The liquid composition comprises a moisture regulator system made from a mixture of C2-C6 monoalkylene polyol and C2-C3 monoalkylene polyol. While another compartment has a hygroscopic powder to absorb the moisture.
Another example is U.S. Patent Application Number 2008/0020220 to Maurer et al., which discloses a PVOH film that has been pretreated exteriorly with a salt solution, to provide resistance to an accidental exposure to water.
Another example is U.S. Pat. No. 7,648,951 to Sharma et al, which discloses a multi-compartment pouch that contains a moisture-sensitive detergent active, and a humectant in a separate compartment to act as a moisture sink for the detergent.
Another example is U.S. Patent Application Number 2004/0182049 to Duffield, which discloses a PVOH film that has been pre-treated on both sides with a mixture of water, salt, and a water-soluble polymer prior to heat sealing. The film treatment increases the dissolution rate of the sealed area.
Another example is U.S. Pat. No. 7,201,819 to Wiedemann et al., which discloses the incorporation of a detergent in liquid, gel or paste form in a sealed package made of a film, wherein the film was pre-treated with glycerol and heat to avoid crumbling and wrinkle formation.
Finally, U.S. Patent Application 2009/0312220 to Boutoille et al. discloses the formation of a multi-compartmented PVA pouch, which contains a powder detergent therein. The PVA film has been pretreated with a wetting agent such as a plasticizer, to increase its malleability prior to pouching.
However, the above-mentioned references neither mention or address the technical problems that are related to pouch-handling under stress conditions, such as cold shock and cracking, or the difficulties of simultaneously flexing the pouch and maintaining the free-flow characteristic of the solid particulate detergent composition.
Thus, an objective of the present invention is to provide a flexible detergent pouch that contains a detergent composition therein. Another objective is to incorporate at least one flexibility-imparting agent within the detergent composition, so that the pouch subsequently becomes flexible and that the detergent composition remains free flowing. A further objective is to provide a detergent pouch whose flexibility does not decrease considerably with time.